Дисертації з теми "Defect dimensions"
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1
Söderberg, Alexander. "Anomalous Dimensions in the WF O(N) Model with a Monodromy Line Defect." Thesis, Uppsala universitet, Teoretisk fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-317546.
Повний текст джерелаАнотація:
General ideas in the conformal bootstrap program are covered. Both numerical and analytical approaches to the bootstrap equation are reviewed to show how it can be manipulated in different ways. Further analytical approaches are studied for theories with defects. We consider the three-dimensional CFT at the corresponding WF fixed point in the O(N) \phi^4 model with a co-dimension two, monodromy defect. Anomalous dimensions for bulk- and defect-local fields as well as one of the OPE coefficients are found to the first loop order. Implications of inserting this defect and constraints that arises from symmetries of the theory are investigated.
2
Pavlovitch, André. "Problemes de structure et de defauts de structure dans les pavages aperiodiques bi-dimensionnels (quasi-cristaux)." Paris 6, 1988. http://www.theses.fr/1988PA066467.
Повний текст джерелаАнотація:
Etude geometrique des proprietes structurales des pavages de penrose bidimensionnels servant de base aux modeles des phases decagonales d'alliages d'aluminium-manganese. Etude de la statistique de propagation privilegies des phasons: les tubes. Description des pavages generalises, obtenus par transformation structurale
3
Нощенко, Сергій Петрович. "Автоматизований вихрострумовий дефектоскоп для моніторингу стану елементів конструкцій літальних апаратів". Master's thesis, КПІ ім. Ігоря Сікорського, 2020. https://ela.kpi.ua/handle/123456789/38193.
Повний текст джерелаАнотація:
Магістерська дисертація містить 112 листа, 25 рисунків, 23 таблиць, 18 джерел за переліком посилань.
У дисертації приведений аналіз елементів конструкцій, як об’єкта НК контролю. Підтверджена доцільність використання вихрострумового неруйнівного контролю для виявлення дефектів типу поверхневих та підповерхневих утомних тріщин та оцінки їх параметрів.
Проведений огляд можливих методів опрацювання прийнятих сигналів за наявними годографами відносної внесеної напруги. Розглянуто типи накладних та прохідних вихрострумових перетворювачів. Проведений аналіз підтвердив доцільність використання вихрострумового перетворювача трансформаторного типу з диференційно з’єднаними вимірювальними котушками.
Підчас аналізу годографів внесеної напруги від дефекту було виявлено можливості більш детального кількісного оцінювання параметрів дефекту за вихідним сигналом ВСП. Отримані за годографом внесеної напруги від дефекту орієнтовні градуювальні характеристики для параметрів дефектів дали змогу прослідкувати особливості зміни фази та амплітуди прийнятого сигналу ВСП від глибини залягання та глибини дефекту. . Запропоновані технічні рішення дають змогу автоматизувати процес контролю щодо прийняття рішення про наявність дефекту та оцінювання числових показників дефектів.The master's dissertation contains 82 letters, 25 figures, 23 tables, 18 sources according to the list of references. The dissertation presents an analysis of structural elements as an object of NC control. The expediency of using eddy current non-destructive testing to detect defects such as surface and subsurface fatigue cracks and evaluate their parameters has been confirmed. A review of possible methods of processing the received signals according to the available hodographs of the relative applied voltage. Types of overhead and through-flow eddy current converters are considered. The analysis confirmed the feasibility of using an eddy current transducer of the transformer type with differentially connected measuring coils. During the analysis of hodographs of the applied stress from the defect, the possibilities of a more detailed quantitative assessment of the defect parameters according to the VSP output signal were revealed. The approximate calibration characteristics for the defect parameters obtained from the hodograph of the applied stress from the defect made it possible to trace the peculiarities of the phase and amplitude change of the received GSP signal from the depth and depth of the defect. . The proposed technical solutions make it possible to automate the process of control over the decision on the presence of a defect and the evaluation of numerical indicators of defects.
4
Fornara, Pascal. "Modélisation et simulation numérique de la croissance des siliciures pour la microélectronique." Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10082.
Повний текст джерелаАнотація:
La miniaturisation des transistors mos n'est plus envisageable sans une etape de metallisation auto-alignee des contacts source/drain et grille (procede salicide: self aligned silicide). Dans les technologies mos actuelles, le siliciure le plus couramment utilise est le disiliciure de titane: tisi#2. La siliciuration ayant une influence a la fois sur les dopants et sur la topographie, elle a un impact evident sur les dispositifs. Afin de garantir des simulations electriques precises, la modelisation des procedes technologiques submicroniques doit donc etre capable de prendre en compte cette etape. Dans ce travail, nous avons developpe un modele general de croissance des siliciures et nous l'avons implemente dans un simulateur de procede bidimensionnel. Nous avons demontre qu'il etait possible de simuler la croissance d'un siliciure aussi bien par diffusion du silicium que par diffusion du metal, ainsi que la siliciuration par depot selectif en phase vapeur. Les parametres du modele ont ete ajustes afin d'obtenir des cinetiques de croissance du tisi#2 en bon accord avec les resultats experimentaux. Nous avons montre que notre modele permettait de rendre compte d'effets topographiques bidimensionnels (absence de croissance sous l'espaceur, courbure de la couche de tisi#2 sur les grilles de polysilicium,), a condition de faire dependre certains parametres des contraintes mecaniques generees pendant la croissance de la couche. L'influence de la siliciuration sur la redistribution des dopants a ete analysee ; la simulation a confirme que la segregation du bore a l'interface tisi#2/si etait responsable de la degradation des resistances d'acces des contacts siliciures sur silicium dope au bore. L'injection de lacunes pendant la siliciuration a egalement ete calibree grace aux resultats experimentaux et, par des simulations de procedes et de dispositifs, nous avons montre que ce phenomene pouvait induire une redistribution des dopants a longue distance. L'outil que nous avons developpe apporte donc une aide a l'optimisation du procede de siliciuration dans les technologies silicium
5
Bogaert, Kevin Christopher. "Defect-driven processing of two-dimensional transition metal dichalcogenides." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122072.
Повний текст джерелаАнотація:
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2019
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 149-161).
Two-dimensional transition metal dichalcogenides (TMDs) are an emerging class of semiconductor materials that offer exciting new properties for future electronic and optoelectronic applications. However, many ongoing challenges related to synthesis and processing must be overcome before this nascent technology can become industrially viable. In this thesis, processing-related phenomena relevant to the fabrication of TMD heterostructures, alloys, and nanoporous membranes are presented. This thesis begins with an investigation of the role of substrate temperature in two-step chemical vapor deposition (CVD) growth of MoS₂/WS₂ heterostructures. We demonstrate diffusion-mediated synthesis of inverted lateral heterostructures following low MoS2 growth temperatures in the second CVD step and homogeneous Mo[subscript x]W[subscript 1-x]S₂ alloyed crystals following higher MoS₂ growth temperatures.
Investigating the nature of this diffusion-mediated process, we identify an energetically favorable atomistic model proposing that transition metal diffusion is driven by a heterogeneous distribution of sulfur vacancies. This model is corroborated by the synthesis of a composition-graded Mo[subscript x]W[subscript 1-x]S₂ alloy crystals in which the final-stage spatial distribution of transition metal atoms correlates with intermediate-stage distribution of point defects. These heterogeneous crystals allow for correlation of the local optical properties with the local composition, demonstrating a variation in photoluminescence intensity spanning two orders of magnitude and reaching the maximum value for equicompositional alloy Mo₀.₅W₀.₅S₂ (x=0.5). Furthermore, the correlation between intermediate-stage distribution of point defects and final-stage spatial distribution of transition metal atoms enables the opportunity for bespoke patterning.
Utilizing a laser annealing technique, we demonstrate the ability to locally induce defects that define the regions of preferential nucleation during subsequent CVD growth. Finally, defect processing is also demonstrated in nanoporous TMD membrane applications. Combining modeling with experimentation, we demonstrate the relationship between vacuum annealing time and temperature with nanopore properties such as average radius and edge structure. Control of these properties is essential for the fabrication of functional nanoporous membrane devices for sensing, filtration, and energy applications. This thesis motivates further work on TMD processing in pursuit of developing a fundamental understanding of the defect-driven diffusion mechanism, a larger library of interesting TMD compositions and structures, as well as industrially viable TMD devices.
by Kevin Christopher Bogaert.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Materials Science and Engineering
6
Schmidt, Robert. "Defects in Higher-Dimensional Quantum Field Theory." Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-71937.
Повний текст джерела
7
Caulier, Yannick. "Surface defect classification based on one-dimensional sensors and structured illumination." Aachen : Shaker, 2008. http://d-nb.info/991379101/04.
Повний текст джерела
8
Rezaei, Seyed Emad. "Defect Engineering: Novel Strengthening Mechanism for Low- Dimensional Zinc Oxide Nanostructures." Wright State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright1532902032338622.
Повний текст джерела
9
任穎華 and Wing-wa Yam. "Two dimensional membrane and bending elements with defects." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31226991.
Повний текст джерела
10
Yam, Wing-wa. "Two dimensional membrane and bending elements with defects /." Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B24367370.
Повний текст джерела
11
Magyar, Peter. "Quelques aspects du transport électronique bidimensionnel : études théoriques en champ magnétique faible et fort." Université Joseph Fourier (Grenoble ; 1971-2015), 1997. http://www.theses.fr/1997GRE10025.
Повний текст джерелаАнотація:
Ce travail presente deux etudes de transport des systemes d'electrons bidimensionnels dans les limites du champ magnetique faible et fort. Premierement, nous avons analyse l'utilite d'une nouvelle approche theorique, destinee a calculer la mobilite limitee par (a) des impuretes ionisees ou par (b) des dislocations. Ce traitement a pour but d'ameliorer la description de l'effet d'ecran. Notre etude a revele que la methode ne represente que des avantages tres limites dans le cas (a), tandis que dans le cas (b) les courbes calculees en fonction de la temperature et de la largeur du puits sont en accord avec les mesures. Deuxiemement, l'effet hall quantique entier a ete etudie dans un potentiel de desordre modele. Le systeme a ete couple a un bain thermique. A partir de l'etat stationnaire d'une equation de boltzmann quantique, les conductivites de hall et dissipative ont ete obtenues en fonction de la temperature pour tous les facteurs de remplissage. Nos resultats sont en accord qualitatif avec les experiences. En outre, ils montrent que, du aux phonons, les plateaux quantifies de la conductivite de hall sont sensiblement plus larges a tres basses temperatures que ceux de la conductivite dissipative.
12
Gladikowski, Jens. "Solitons in low-dimensional sigma models." Thesis, Durham University, 1997. http://etheses.dur.ac.uk/5077/.
Повний текст джерелаАнотація:
The aim of this thesis is to study topological soliton solutions in classical field theories, called sigma models, on a three-dimensional space. In chapter 1 we review the general field-theoretical framework of classical soliton solutions and exemplify it on the main features of the 0(3) σ-model and the Abehan Higgs model in (2+1) dimensions. In chapter 2 a U(l)-gauged 0(3) σ-model is discussed, where the behaviour of the gauge field is determined by a Chern-Simons term in the action. We find numerical solutions for radially symmetric fields and discuss those of degree one and two. They carry a non-vanishing angular momentum and can be interpreted as classical anyons. A similar model is studied in chapter 3. Here the potential is of Higgs-type and chosen to produce a Bogomol'nyi model where the energy is bounded from below by a linear combination of the topological degree of the matter fields and the local U(l)-charge. Depending on internal parameters, the solutions are solitons or vortices. We study them numerically and prove for a certain range of the matter field's vacuum value that there cannot be a 1-soliton.In chapter 4 we discuss a modified 0(3) σ-model in (3+0) dimensions. The topological stability of the solitons is here imphed by the degree of the map S(^3) → S(^2), which provides a lower boundon the potential energy of the configuration. Numerical solutions are obtained for configurations of azimuthal symmetry and the spectrum of slowly rotating solitons is approximated. Chapter 5 deals with a theory where the fields are maps IR(^2+1) → CP(^2). The Lagrangian includes a potential and a fourth-order term in the field-gradient. We find a family of static analytic solutions of degree one and study the 2-soIiton configuration numerically by using a gradient-flow equation on the moduli space of solutions. We conclude this thesis with a brief summary and give an outlook to open questions.
13
Rice, Marie C. "Healing of defects in a two-dimensional granular crystal." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92204.
Повний текст джерелаАнотація:
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 52-54).
Using a macroscopic analog for a two dimensional hexagonal crystal, we perform an experimental investigation of the self-healing properties of circular grain defects with an emphasis on defect orientation. A circular grain defect is introduced into a nearly perfect hexagonal array of millimeter-sized spherical brass particles enclosed in a square tray. The array is oscillated uniaxially, causing the particles to vibrate randomly with respect to each other, which in turn induces the curved grain boundary around the misoriented defect region to migrate toward its center of curvature. Images of the healing crystal are acquired and analyzed to determine particle locations and quantify the size of the defect at prescribed time intervals. This procedure was repeated ninety-four times in order to collect data on a range of misorientations. In some cases, the misorientation angle varied significantly during healing so both initial misorientation and time averaged misorientation angle were considered as possible driving variables for healing rate. Healing times were fit to an exponential curve dependent on misorientation angle but there was a high degree of scatter from this correlation. Despite this variation in path shape, there was some correlation between healing time and misorientation, though there was significant scatter. In an effort to identify the source of this scatter by differentiating between defects with different healing times but nearly the same misorientation angle, the time dependence of healing rate was investigated. This more detailed examination of the time evolution of defect size revealed substantial variation in time dependence type. Both linear and nonlinear time dependence of defect area size was observed among the healing samples. The nonlinear time dependence of defect size was not common among defects with low healing times. However, degree of linearity did not effectively distinguish between defects with similar misorientation and widely different healing times nor did it correlate meaningfully with misorientation. Though the self-healing behavior of grain defects has not yet been fully characterized, there is evidence that geometric parameters influence overall healing time.
by Marie C. Rice.
S.B.
14
Wong, Tsz Chun. "Experimental and theoretical investigation of optical nonlinearity in one-dimensional photonic crystal with central defect mode /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202009%20WONG.
Повний текст джерела
15
Caulier, Yannick [Verfasser]. "Surface Defect Classification Based on One-Dimensional Sensors and Structured Illumination / Yannick Caulier." Aachen : Shaker, 2008. http://d-nb.info/1161303618/34.
Повний текст джерела
16
Schnur, Christopher. "Electron Beam - Powder Bed Fusion Of Alloy 718 : Influences Of Contour Parameters On Surface And Microstructural Characteristics." Thesis, Högskolan Väst, Avdelningen för Industriell ekonomi, Elektro- och Maskinteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-14318.
Повний текст джерелаАнотація:
Additive Manufacturing (AM) is an uprising manufacturing process for parts with complex geometries and low production quantities. Within the layer-wise building process, less additional processes are needed, to produce the parts. This allows a building of parts within a reasonable time- and costs-range. Especially industries, such as aerospace industry, can profit from AM. Electron beam – Powder bed fusion (EB-PBF) is a common technique, within AM, to produce metallic parts out of special alloys such as Alloy 718. This superalloy is a Nickle-Iron based alloy that has high mechanical properties, even in elevated temperatures (up to 650ºC). The combination of such material properties with high geometrical freedom creates new opportunities for the industry. However, it must be noted that a significant drawback of AM-techniques is the need for post-processing because of surface roughness- and microstructural characteristics. Commonly, the produced parts utilize mechanical post process such as milling to provide good surface roughness and dimensional accuracy. To reduce the surface roughness in the contour region, and therefore reduce the amount of mechanical post-processing, the present survey elaborates the effect of relevant parameters on contours such as the number of contours, scanning speed, focus offset and beam current. By using Design of Experiments (DOE), two batches were carried out: one screening batch and a two-level-full factorial design. In those batches, 15×15×15 mm cubes were printed with various parameters and, after that, analysed by using White light interferometry (WLI), Optical microscopy (OM) and Scanning electron microscopy (SEM). Furthermore, the program ImageJ was used to perform porosity and melt pool measurements. It had been observed that the number of contours had quite a considerable impact on the final surface roughness and the number of defects. Samples with two contours, instead of only one, tend to have a lower surface roughness. Nevertheless, the parameters and their interaction were found to have fundamental effects on the resulting surface roughness and microstructure.
17
Youssef, Amanda. "Three-dimensional defect characterization : focused ion beam tomography applied to tin sulfide thin films." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92112.
Повний текст джерелаАнотація:
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 81-86).
Porosity is postulated to be one of the reasons for the low efficiency of tin sulfide-based devices. This work is a preliminary investigation of the effects of two film growth parameters deposition rate and substrate temperature - on porosity. We employ the focused ion beam tomography technique to characterize and quantify porosity in tin sulfide thin films. We then generate 3D reconstructions of pores inside milled volumes from the films and quantify pore volumes. To explain the results, we employ nucleation theory and develop two different models: (a) a thermodynamic model that assumes pores form primarily from an effect known as "self-shadowing," whereby growth-rate anisotropy results in some grains that grow faster than their neighbors, and (b) a kinetic model that assumes a diffusion-driven process of void formation. We show that both models qualitatively support the experimental results, providing insight into process-structure relations that may improve film quality during growth.
by Amanda Youssef.
S.M.
18
Chen, Qu. "Structural studies of defects in two-dimensional materials with atomic resolution." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:392f2b1d-0488-4d10-96d9-817def04db2a.
Повний текст джерелаАнотація:
Defective structures in two-dimensional (2D) materials have been proved to have significant influences on the materials' properties. Understanding structural defects in 2D materials at atomic scale is therefore required. With the use of advanced imaging techniques, one of the main approaches applied in this project was aberration-corrected transmission electron microscopy (AC-TEM), the structures are able to be resolved with single-atom sensitivity with the reduction of both spherical aberration and the influence of chromatic aberration. This laid the foundation for the first two experiments, which involve the bond length measurement of each C-C bond within three types of divacancies and Si-C bonds at graphene edges. The former explains the tendency of bond rotations within the divacancies from the perspective of strain inside the defective areas and surrounding lattice; the latter revels the interactions between isolated Si atoms and zigzag/armchair graphene edges. The use of in-situ heating holder in the AC-TEM makes the direct visualization of structures and their dynamics at elevated temperatures possible. The Si-graphene edge interactions, as well as the following two experiments are all designed to study the high-temperature performances for different systems. Gold nanoclusters are introduced to monolayer graphene by thermal evaporation to study the interaction between gold and graphene at elevated temperature. Due to the strong interaction between gold and graphene, gold crystals are able to adapt to planar configurations with two different crystalline forms, and an epitaxial relationship was found for planar gold crystals and graphene. Atomically flat and long line defects and zigzag edges in monolayer molybdenum disulfide (MoS2) are successfully created by in-situ thermal annealing. The relationship between S vacancy mobility and defect forms are revealed based on the experiment. High-temperature atomic configurations of line defects and edge terminations are resolved in the first time. Their electronic properties are also explored with the support of density functional theory calculations.
19
Saxton, Patrick C. (Patrick Charles) 1975. "Reducing powder bed layer defects in slurry-based three dimensional printing." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9423.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1999.Includes bibliographical references (leaf 141).
Slurry-based Three Dimensional Printing is being used to create ceramic parts directly from CAD files. Discrete slurry layers are deposited, into which a binder material is selectively ink-jet printed. This process is repeated until the last layer of the powder bed is deposited. Afterwards, the powder bed is re-dispersed in water, leaving behind the printed green part. The green part is then sintered to full density. This thesis focuses on methods of depositing the slurry layers. Currently, slurry layers are deposited by nozzle rastering. In this approach, a nozzle mounted to an x-y linear positioning system deposits adjacent discrete lines of slurry on a powder bed. Powder beds produced by nozzle rastering contain defects that occur between line and layer interfaces. The top surface has an inherent roughness due to the peaks and valleys between discrete lines. Line merging is a new method of slurry layer deposition that has been developed in an effort to eliminate inter-line defects, improve layer surface finish, and increase throughput This new technique has been used to rapidly produced slurry layers containing fewer internal defects and smooth surface finishes. Line merging occurs when adjacent lines of slurry are deposited in rapid succession such that they merge together prior to slip casting. Line merging differs from nozzle rastering in two ways: lines are deposited in only one direction (during the return pass the nozzle is put into a catch position), and the cycle time between depositing lines is reduced from approximately I second to as little as 0.1 second. A model was developed in an effort to identify the conditions required to achieve successful line merging, while avoiding layer defects such as bubbling and irregular surface finish caused by slurry migration. This model emphasized three relationships: the ratio of cycle time for line deposition to slip casting time for a slurry layer, the ratio of line width to line spacing, and the inverse of the width of the wet slurry zone where lines have merged prior to slip casting. A 3-D plot was constructed relating an objective function comprised of the three relationships to the control parameters (flow rate divided by nozzle velocity and cycle time). A plot for each alumina slurry solids loading was used to guide experiments. These experiments supported the model, though some relationships were proved more accurate than others. The model was ultimately used to target the ideal line merging conditions that were used to produced a 60 layer alumina powder bed out of 50 micron thick layers of 18 vol% alumina slurry. This powder bed exhibited excellent surface finish, with a maximum variation of 11 microns peak to valley. SEM analysis of cross-sections revealed that internal defects between deposited lines, previously seen with nozzle rastering, had been eliminated. Micro-bubbles along the interface between layers persisted, however. Follow-up SEM analysis of a 5 layer powder bed built with 22 vol% alumina slurry revealed no inter-line or inter-layer defects.
by Patrick C. Saxton.
S.M.
20
Stieler, Daniel Paul. "Characterization of defect cavities and channel-drop filters in the three dimensional woodpile photonic crystal." [Ames, Iowa : Iowa State University], 2008.
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21
Afsharian, Mohsen [Verfasser]. "The Two-Dimensional, Rectangular, Guillotineable-Layout Cutting Problem with Defects / Mohsen Afsharian." Aachen : Shaker, 2013. http://d-nb.info/1051575575/34.
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22
Xu, Tao. "Low-dimensional atomic-scale multiferroics in nonmagnetic ferroelectrics from lattice defects engineering." Kyoto University, 2017. http://hdl.handle.net/2433/227622.
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23
Lassige, Timothy A. "Comparison of septal defects in 2-D and 3-D echocardiography using active contour models." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/13839.
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O'Neill, Darren Frances. "An investigation of excrescence drag due to manufacturing defects on two-dimensional surfaces." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246541.
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Boyers, Albert S. "SPECT myocardial perfusion scans : a left ventricular defect size estimation algorithm and a three dimensional computer simulation." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/14879.
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Law, Alex. "Dimensions of restructuring : state, capital and labour in the defence industry in Scotland." Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/21351.
Повний текст джерелаАнотація:
This thesis examines changing relations in the defence industry. The defence industry is peculiar in important respects, not least because of the central role of the state in shaping the structure of the industry. During the Cold War excess capacity was preserved intact to meet state demands for armament technology and the defence industry was protected from more the more general decline of manufacturing in Britain. With attempts to restructure the arms complex in Britain, the disturbance of decades of structural stasis allowed a study of industrial change in concentrated form. A leading edge military electronics firm, Ferranti (now GEC-Marconi) and a naval repair yard, Rosyth dockyard (now Babcock Rosyth Defence), were studied to understand the precise forms industrial change took and its historically contingent nature. Semi-structured interviews were conducted with key sectors within the firms and primary and secondary documentary sources consulted. The first part of the thesis sets out the general field of study, considering general questions of restructuring and the nature of the defence industry. The historical pattern of defence industry in Scotland is also discussed. Traditional warshipbuilding was joined by advanced electronics capacity during the Cold War when Scotland became a strategic location for military support and production activities. Part Two contains the case study material. The historical development of each firm in its external relation to the state and internal workplace relations is set out. Experiences of restructuring are considered next, taking into account the impact of privatisation, marketisation and changing products markets. Changing contours of the workforce and worker resistance to and compliance with restructuring is discussed. Part three then interprets the case studies within a wider Marxist political economy.
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Baniasadi, Fazel. "Structure Characterization and Electronic Properties Investigation of Two-Dimensional Materials." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/103904.
Повний текст джерелаАнотація:
This dissertation will have three chapters. In chapter one, a comprehensive review on defects in two dimensional materials will be presented. The aim of this review is to elaborate on different types of defects in two dimensional (2D) materials like graphene and transition metal dichalcogenides (TMDs). First, different types of point and line defects, e.g. vacancies, anti-sites, guest elements, adatoms, vacancy clusters, grain boundaries, and edges, in these materials are categorized in terms of structure. Second, interactions among defects are discussed in terms of their rearrangement for low-energy configurations. Before studying the electronic and magnetic properties of defective 2D materials, some of the structures are considered in order to see how defect structure evolves to a stable defect configuration. Next, the influence of defects on electronic and magnetic properties of 2D materials is discussed. Finally, the dynamic behavior of defects and 2D structures under conditions such as electron beam irradiation, heat treatment, and ambient conditions, is discussed. Later as a case study, defects in a two dimensional transition metal dichalcogenide will be presented. Among two-dimensional (2D) transition metal dichalcogenides (TMDs), platinum diselenide (PtSe2) stands at a unique place in the sense that it undergoes a phase transition from type-II Dirac semimetal to indirect-gap semiconductor as thickness decreases. Defects in 2D TMDs are ubiquitous and play crucial roles in understanding and tuning electronic, optical, and magnetic properties. Here intrinsic point defects in ultrathin 1T-PtSe2 layers grown on mica were investigated through the chemical vapor transport (CVT) method, using scanning tunneling microscopy and spectroscopy (STM/STS) and first-principles calculations. Five types of distinct defects were observed from STM topography images and the local density of states of the defects were obtained. By combining the STM results with first-principles calculations, the types and characteristics of these defects were identified, which are Pt vacancies at the topmost and next monolayers, Se vacancies in the topmost monolayer, and Se antisites at Pt sites within the topmost monolayer. Our study shows that the Se antisite defects are the most abundant with the lowest formation energy in a Se-rich growth condition, in contrast to cases of 2D molybdenum disulfide (MoS2) family. Our findings would provide critical insight into tuning of carrier mobility, charge carrier relaxation, and electron-hole recombination rates by defect engineering or varying growth condition in few-layer 1T-PtSe2 and other related 2D materials. Also, in order to investigate the layer dependency of vibrational and electronic properties of two dimensional materials, 2M-WS2 material was selected. Raman spectroscopy and DFT calculation proved that all Raman active modes have a downshift when material is thinned to few layers (less than 5 layers). It was proven that there is a strong interaction between layers such that by decreasing the number of layers, the downshift in Raman active modes is mostly for the ones which belong to out-of-plane atomic movements and the most downshift is for the Ag2 Raman active mode. Also, I investigated the effect of number of layers on the band structure and electronic properties of this material. As the number of layers decreases, band gap does not change until the materials is thinned down to only a single monolayer. For a single monolayer of 2M-WS2, there is an indirect band gap of 0.05eV; however, with applying in-plane strain to this monolayer, the material takes a metallic behavior as the strain goes beyond ±1%.Doctor of Philosophy
Graphite (consisting of graphene as building blocks) and TMDS in bulk form are layered and with exfoliation one can reach to few layers which is called two-dimension. Two dimensional materials like graphene have been used in researches vastly due to their unique properties, e.g. high carrier mobility, and tunable electronic properties. Transition metal dichalcogenides (TMDs) with a general formula of MX2, where M represents transition metal elements (groups 4-10) and X represents chalcogen elements (S, Se or Te), are another family of two-dimensional materials which have been extensively studied in the past few years. Besides exfoliation, there are also synthesis methods to produce two dimensional materials, e.g. chemical vapor deposition and chemical vapor transport. Normally, after synthesizing these materials, researchers investigate structure and electronic properties of these materials. There might be some atoms which no longer exist in the structure; hence, those are replaced by either vacancies or other elements which all of them are called defects. In chapter 1, defects in graphene and transition metal dichacolgenides were investigated, carefully. Later, dynamic behavior of defects in these materials were investigated and finally, the effect of defects on the electronic properties of the two dimensional materials were investigated. Chapter two talks about a case study which is two dimensional 1T-PtSe2. In this chapter, 5 different kinds of defects were studied using scanning tunneling microscopy and spectroscopy investigations and density functional theory was used to prove our assumptions of the origin of defects. Also, another thing which is investigated by researcher is that how atoms in two dimensional materials vibrate and how the number of layers in the two dimensional material influences vibrations of atoms. Other than this, electronic properties of these materials is dependent upon the number of layers. When these materials are synthesized, there is a stress applied to the material due the mismatch between the material and its substrate, so it is worth investigating the effect of stress (strain) on the structure, and electronic properties of the material of interest. For this purpose, 2M-WS2 was exfoliated on Si/SiO2 substrate and the layer dependency of its vibrational modes was investigated using Raman spectroscopy and density functional theory calculation. Also, in order to investigate the influence of stress (strain) on the electronic properties of two dimensional 2M-WS2, a single monolayer of this materials underwent a series of strains in density functional theory calculations and the effect of strain on the electronic properties of this material was investigated.
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Tuesday, Andrew J. "Modeling Atomic Defects in a Two-Dimensional Lennard-Jones Lattice Using Molecular Dynamics Simulations." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1334579948.
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Hsiao, Ming-Siao. "Crystallization, Crystal Orientation and Morphology of Poly(Ethylene Oxide) Under One Dimensional Defect-Free Confinement on the Nanoscale." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1247266725.
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Krymowski, Kevin E. "The Effect of Ligand Variation on Two-Dimensional Materials." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1495802952188467.
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Jafri, Syed Hassan Mujtaba. "Building Systems for Electronic Probing of Single Low Dimensional Nano-objects : Application to Molecular Electronics and Defect Induced Graphene." Doctoral thesis, Uppsala universitet, Tillämpad materialvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-160630.
Повний текст джерелаАнотація:
Nano-objects have unique properties due to their sizes, shapes and structure. When electronic properties of such nano-objects are used to build devices, the control of interfaces at atomic level is required. In this thesis, systems were built that can not only electrically characterize nano-objects, but also allow to analyze a large number of individual nano-objects statistically at the example of graphene and nanoparticle-molecule-nanoelectrode junctions. An in-situ electrical characterization system was developed for the analysis of free standing graphene sheets containing defects created by an acid treatment. The electrical characterization of several hundred sheets revealed that the resistance in acid treated graphene sheets decreased by 50 times as compared to pristine graphene and is explained by the presence of di-vacancy defects. However, the mechanism of defect insertion into graphene is different when graphene is bombarded with a focused ion beam and in this case, the resistance of graphene increases upon defect insertion. The defect insertion becomes even stronger at liquid N2 temperature. A molecular electronics platform with excellent junction properties was fabricated where nanoparticle-molecule chains bridge 15-30nm nanoelectrodes. This approach enabled a systematic evaluation of junctions that were assembled by functionalizing electrode surfaces with alkanethiols and biphenyldithiol. The variations in the molecular device resistance were several orders of magnitude and explained by variations in attachment geometries of molecules. The spread of resistance values of different devices was drastically reduced by using a new functionalization technique that relies on coating of gold nanoparticles with trityl protected alkanedithiols, where the trityl group was removed after trapping of nanoparticles in the electrode gap. This establishment of a reproducible molecular electronics platform enabled the observation of vibrations of a few molecules by inelastic tunneling spectroscopy. Thus this system can be used extensively to characterize molecules as well as build devices based on molecules and nanoparticles.
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Hartman, Christie Ann. "The genetic etiology of attention-deficit/hyperactivity disorder and its dimensions: Linkage to chromosome 6p." Diss., Connect to online resource, 2005. http://wwwlib.umi.com/dissertations/fullcit/3186932.
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Foteinopoulou, Stavroula. "Electromagnetic Wave Propagation in Two-Dimensional Photonic Crystals." Washington, D.C. : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Science ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2003. http://www.osti.gov/servlets/purl/822058-9BqHHS/native/.
Повний текст джерелаАнотація:
Thesis (Ph.D.); Submitted to Iowa State Univ., Ames, IA (US); 12 Dec 2003.Published through the Information Bridge: DOE Scientific and Technical Information. "IS-T 2048" Stavroula Foteinopoulou. 12/12/2003. Report is also available in paper and microfiche from NTIS.
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Perez, Blanco Isabel Cristina [Verfasser]. "A model development for reconstruction of three-dimensional defects based on MFL signals / Isabel Cristina Perez Blanco." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2020. http://d-nb.info/1224883586/34.
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Asenjo, Andrews Daniel Arthur. "Sobre la Transición Sólido-Líquido y la Inestabilidad Mecánica Provocada por Defectos en Dos Dimensiones." Tesis, Universidad de Chile, 2009. http://repositorio.uchile.cl/handle/2250/102072.
Повний текст джерелаАнотація:
Se estudió un sistema de 3,6864×104 partículas que interactúan a través del potencial de
Lennard-Jones mediante dinámica molecular, usando un código paralelo que integra las ecuaciones
de movimiento diseñadas para simular un sistema a tensor de presiones y temperatura
constantes (NPT) en dos dimensiones.
Se investigó una región del espacio de fase correspondiente a presión nula y temperaturas
cercanas al punto de fusión, para comparar los resultados con las predicciones de la teoría
de Kosterlitz, Thouless, Halperin, Nelson y Young (KTHNY). En esta teoría la fusión de un
sólido bidimensional, provocada por los defectos topológicos, ocurre a través de dos transiciones
de fase continuas. En la primera transición se pierde el orden traslacional y en la segunda
el orden orientacional, resultando en un líquido que carece de orden. Los mecanismos que
provocan la fusión tienen una estrecha relación con el comportamiento y la dinámica de los
defectos, particularmente las dislocaciones y el desligamiento de pares de ellas. En la teoría
KTHNY las constantes elásticas se acercan a un valor universal cuando el sólido se acerca a
su temperatura de fusión.
Con el n de explorar la compatibilidad del sistema simulado con la teoría se ha estudiado
el comportamiento de la entalpía, las constantes elásticas, la fracción de defectos y se ha hecho
un análisis visual de los defectos en función de la temperatura. También se investigó el número
de iteraciones que demora el sistema en llegar al equilibrio en función de la temperatura y
las condiciones iniciales.
Se ha observado una transición de fase sólido líquido entre las temperaturas reducidas
0,40725 (sólido) y 0,4095 (líquido). Se ha estudiado el tiempo que demora el sistema en
llegar al equilibrio en función de la temperatura. Al acercarse a la temperatura de transición
este tiempo aumenta. El comportamiento de las propiedades mecánicas del sistema está en
acuerdo con la teoría KTHNY. El análisis de los defectos presentes en el sistema a diferentes
temperaturas permite concluir que en el sólido frío sólo se observan pares de dislocaciones
ligadas mientras que al subir la temperatura y acercarse a la transición de fase se forman
regiones densas de defectos y los pares se empiezan a desligar. En el líquido se ve una mayor
concentración de defectos muy desordenados. Este escenario está de acuerdo con la teoría
KTHNY que dice que la fusión ocurre a partir del desligamiento de pares de dislocaciones.
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Ive, Jeremy George Augustus. "The local dimensions of defence : the standing army and militia in Norfolk, Suffolk and Essex, 1649-1660." Thesis, University of Cambridge, 1987. https://www.repository.cam.ac.uk/handle/1810/244865.
Повний текст джерелаАнотація:
Thesis: The local dimensions of defence: the standing army and militia in Norfolk, Suffolk, and Essex 1649-1660. Par t l: Interregnum governments faced numerous threats to their security and military power: internally from Royalist conspiracies and political dissidence, and externally from the danger of a combined Royalist and foreign invasion. The Eastern Counties were of strategic importance to Interregnum governments because of their proximity to London and the Continent, and because of their considerable economic resources. Interregnum governments were able to maintain their control over the region, and draw upon its resources for defence through the region's local and central administrative structures. Part II: The first arm of the Interregnum system of defence was the standing army. This consisted first of the units of horse and foot stationed in the region. The horse were used primarily to respond quickly to internal threats. The foot were stationed in the region primarily to await embarkation for foreign service. The coast was protected by a series of fortifieti garrisons, the governors of which played a key role in coordinating the defence and security of the region. A uniform assessment was levied which provided a sound basis for the pay and supply of the standing forces. Part Ill: The standing army was complemented by the militia. Like the standing forces, the traditional county and borough forces were reorganized and put on a sound basis after the Civil War. The new organization provided the framework for local defence up to and after the Restoration. Within this framework, Interregnum gover nments experimented with various select militias, but with only limited success. Both the 'general' and 'select' militias were administered in the localities by a group of trusted appointees, who worked closely with the garrison governors, and later with the Major-Generals of 1655 and 1659 to coordinate the regions' defence and security. The financial structure of the militia was based on a uniform and statutorily defined scale of rates. Conclusion: Together the standing army and militia formed part of a single system comprised of three mutually dependent elements: the deployment of men and materials , the maintenance of security, and the raising of funds. The system was put on an efficient basis during the Interregnum and embodied the ideal of publicly uniform administration which characterized Interregnum government as a whole.
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Zareie, Rajani Hamid Reza. "Development of a three-dimensional multi-scale model to study the formation of solidification defects in fusion welding." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57601.
Повний текст джерелаАнотація:
One of the long-standing challenges in joining of aluminum alloys is the occurrence of
solidification defects, i.e. hot cracking and porosity, since these defects significantly increase manufacturing costs. This research project investigates the formation of solidification defects through development of a novel and comprehensive 3-D multi-scale and multi-physics numerical study and then application to the GTA welding of the aluminum alloy AA6061. The developed multi-scale model is composed of four different modules: 1) Solidification, 2) Deformation, 3) Fluid flow, and 4) Defect formation. The solidification module numerically reconstructs the 3-D microstructure of semisolid welds using a granular model of solidification. Specifically, a modified Voronoi tessellation algorithm is used to generate an unstructured grid representing the weld microstructure. The reconstructed microstructure contains both columnar and equiaxed grains and varies as a function of welding process parameters. Then, the Scheil equation is used in combination with the temperature field obtained through the Rosenthal equation and the reconstructed 3D microstructure to simulate solidification. This module outputs the evolving 3D structure of the semisolid weld composed of solid grains and a network of micro liquid channels for use by the deformation and fluid flow modules as the simulation geometry. The deformation module analyzes via finite elements the deformation of the semisolid weld due to externally applied strains and self-induced strains such as thermo-mechanical strains and solidification shrinkage in order to obtain local strain rates within the micro liquid channels. The local strain rates outputted by the deformation module feed a fluid flow analysis module in which the pressure field within the semisolid weld is calculated. Finally, the defect formation module uses various defect formation models to link the pressure field and the local strain rates to the formation of solidification defects including micro cracks and hydrogen porosity.Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate
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Kruták, Martin. "Automatická kontrola kvality výrobku z obrazu." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2019. http://www.nusl.cz/ntk/nusl-403118.
Повний текст джерелаАнотація:
The goal of this thesis is to create overall, automatic and non-contact quality control of a pellet. The issue is divided into two separate parts. The first part deals with precise dimensional measuring of pellet - its length and head diameter so that it is precise and reasonably fast. Precise measuring is achieved with help of algorithms which achieve the sub-pixel precision by polynomial approximation of the edges extracted from the image gradients. The second part deals with the defects of a pellet. Detecting defects like longitudinal furrows or skirt cuts is achieved with convolutional neural networks. The measurement modules work with the resulting precision up to 0.025 mm in case of length measuring and up to 0.01 mm in case of head diameter measuring. In case of defect detections, neural network shows very high classification success rate. The contribution of this thesis is a presentation of innovative approaches in automatic quality control of pellets with use of neural networks and a demonstration of its usage in real manufacturing process.
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Das, Ajoy Kumar. "Health Assessment of Three Dimensional Large Structural Systems Using Limited Uncertain Dynamic Response Information." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/268597.
Повний текст джерелаАнотація:
A novel system identification (SI)-based structural health assessment (SHA) procedure has been developed integrating several theoretical and implementation aspects. The procedure assesses health of structures using limited noise-contaminated dynamic responses and without using input excitation information. Since most practical structures are three dimensional (3D), the procedure has been developed for general 3D structures, represented by finite elements (FEs). The procedure identifies defects by tracking the changes in the stiffness of the elements in the FE representation. Once a defective element is identified, defect spot can be identified accurately within the defective element. The procedure is denoted as 3D Generalized Iterative Least-Squares Extended Kalman Filter with Unknown Input (3D GILS-EKF-UI) and implemented in two stages. In Stage 1, based on the available responses, substructure(s) are selected and the 3D GILS-UI procedure is used to generate the unknown input excitation, stiffness parameters of the elements in the substructure, and two Rayleigh damping coefficients. Using information from Stage 1, stiffness parameters for the whole structure are identified using EKF with Weighted Global Iteration (EKF-WGI) in Stage 2. The procedure accurately identified defect-free and defective states of various 3D structures using only analytically generated limited responses. To increase the robustness, 3D GILS-EKF-UI has been extended to develop an integrated structural health assessment strategy, denoted as Iterative Least-Squares Extended Kalman Filter with Unknown Input and Advanced Digital Integration Technique (ILS-EKF-UI-ADIT). The procedure has been implemented in three stages. In Stage 1, an advanced digital integration technique (ADIT) is implemented for post-processing of noise-contaminated acceleration time-histories, addressing all major challenges of digital integration. It also overcomes non-convergence issue in Stage 2 that arises due to phase-shift and amplitude errors. In Stage 2, substructure(s) are identified using the least-squares procedure. In Stage 3, stiffness parameters for the whole structure are identified using the EKF-WGI procedure. ILS-EKF-UI-ADIT has been verified in presence of relatively large noise in the acceleration time-histories, measured at small part(s) of defect-free and defective structures, without using excitation information. The SHA procedure is robust and has the potential to be applied for the health assessment, maintenance, retrofitting, and life extension of existing structural systems.
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Lee, Soon Gi. "Quantitative Characterization of Processing-Microstructure-Properties Relationships in Pressure Die-Cast Mg Alloys." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11552.
Повний текст джерелаАнотація:
The central goal of this research is to quantitatively characterize the relationships between processing, microstructure, and mechanical properties of important high-pressure die-cast (HPDC) Mg-alloys. For this purpose, a new digital image processing technique for automatic detection and segmentation of gas and shrinkage pores in the cast microstructure is developed and it is applied to quantitatively characterize the effects of HPDC process parameters on the size distribution and spatial arrangement of porosity. To get better insights into detailed geometry and distribution of porosity and other microstructural features, an efficient and unbiased montage based serial sectioning technique is applied for reconstruction of three-dimensional microstructures. The quantitative microstructural data have been correlated to the HPDC process parameters and the mechanical properties. The analysis has led to hypothesis of formation of new type of shrinkage porosity called, gas induced shrinkage porosity that has been substantiated via simple heat transfer simulations. The presence of inverse surface macrosegregation has been also shown for the first time in the HPDC Mg-alloys. An image analysis based technique has been proposed for simulations of realistic virtual microstructures that have realistic complex pore morphologies. These virtual microstructures can be implemented in the object oriented finite elements framework to model the variability in the fracture sensitive mechanical properties of the HPDC alloys.
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Infante, Fulvio. "Development of magnetic microscopy techniques for failure localization on three-dimensional circuits." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14394/document.
Повний текст джерелаАнотація:
Dans ce travail, de nouveaux développements sur les techniques de localisation des composants électroniques en trois dimensions sont montrés. Ces développements sont réalisés grâce à l'introduction de simulations pour une technique déjà existante: la Microscopie Magnétique (MM). Dans la première partie, l'état de l'art de l'assemblage des nouveaux composants tridimensionnels est décrit. Il est ensuite suivi par une description du processus FA actuel, tout en le gardant aussi général que possible. Une description de la fiabilité des dispositifs, en fonction de leur temps d'utilisation est décrite, permettant au lecteur de comprendre pourquoi initialement l'Analyse de défaillance est apparue nécessaire. L'ensemble du processus d'analyse de défaillance est alors décrit de manière générale, à partir de la caractérisation électrique du défaut, jusqu'aux résultats finaux. Dans la deuxième partie est ensuite expliquée dans le détail la technique de microscopie magnétique, qui utilise les propriétés des champs magnétiques générés par les courants, et permet de localiser précisément les défauts des composants électroniques standards. La troisième partie de ce travail est consacrée à l'approche de simulation (SA): une nouvelle méthodologie développée pour étendre les capacités des techniques de microscopie magnétique. Le principe de base est de comparer la simulation magnétique générée par des hypothèses de distributions de courant aux acquisitions magnétiques de la distribution réelle. L'évaluation de la corrélation entre les deux donnera ensuite une mesure de la distance entre eux. Par ailleurs, cette approche est capable de surmonter les limitations de la technique: le défaut peut désormais être localisé en trois dimensions. Enfin, dans la quatrième partie, la nouvelle technique est appliquée et validé sur un ensemble de cas d'étudesIn this work, new developments on localization techniques for three-dimensional electronic components are shown and demonstrated. These are performed through the introduction of simulations for an already existing technique: Magnetic Microscopy (MM). In the first part, a state of the art of new three-dimensional components assembly is described. It is then followed by an up to date FA process description, while keeping it as general as possible. A description of component reliability, in function of the time of usage of such devices is shown, allowing the reader to understand why the need for Failure Analysis arose in the first place. The whole process of Failure Analysis is then described in a general way, starting from the electrical characterization of the defect, to the final results. The second part then explains the Magnetic Microscopy technique in more detail. This technique uses the properties of the magnetic fields, which are generated by the currents, to precisely localize the defects in standard electronic components. The third part of this work is dedicated to the Simulation Approach (SA): a new methodology developed to extend the capabilities of Magnetic Microscopy techniques. The basic principle is that of comparing magnetic simulations generated by hypothetical current distributions to the magnetic acquisitions of the real current distribution. The evaluation of the correlation between the two then gives a measurement of the distance between them. This approach is able to overcome the previous limitations of the technique: the defect can now be localized in three dimensions. Finally, in the fourth part the new technique is applied and validated on a set of case studies
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Sreedhar, Aswin. "Automatic techniques for modeling impact of sub-wavelength lithography on transistors and interconnects and strategies for testing lithography induced defects." Connect to this title online, 2008. http://scholarworks.umass.edu/theses/80/.
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Hunter, Sri Mulyati. "The "changing dimensions" of the Australia-Indonesia bilateral relationship from 1996 to October 2002 in the defence and security context /." Diss., Title page, contents and introduction only, 2002. http://web4.library.adelaide.edu.au/theses/09AR/09arh947.pdf.
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Neves, Alyson Bruno Fonseca. "VÓRTICES NA REDUÇÃO DIMENSIONAL DO MODELO DE MAXWELL-CARROLL-FIELD-JACKIW-HIGGS." Universidade Federal do Maranhão, 2012. http://tedebc.ufma.br:8080/jspui/handle/tede/736.
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This monograph presents the study of vortices BPS in a model obtained by dimensional reduction of the (1+3)−D Maxwell-Carroll-Field-Jackiw-Higgs s electrodynamics to (1+2)−D. The Maxwell-Carroll-Field-Jackiw-Higgs model is defined by the following Lagrangian density L1+3 = −14FμνFμν −14 ϵμνκλ (kAF )μ AνFκλ + |Dμϕ|2 − V (|ϕ|), the first two terms constitute the CPT-odd electrodynamics of the standard model extension (SME). The term ϵμνκλ (kAF )μ AνFκλ is called the Carroll-Field-Jackiw s term. The dimensional reduction of this model is given by the following Lagrangian density L1+2 = − 14FμνFμν +s4 ϵμνκAμFνκ +12∂μψ∂μψ −12ϵμνκ (kAF )μ ψ∂νAκ−12 ϵμκν (kAF )μ Aκ∂νψ + |Dμϕ|2 − e2ψ2 |ϕ|2 − V (|ϕ|2 , ψ), it is observed that if (kAF )μ = 0 we obtain the Maxwell-Chern-Simons-Higgs (MCSH) model. This way, our planar model is a MCSH model modified by an interaction between the gauge field Aμ and the neutral scalar field ψ whose coupling constant is (kAF )μ, the Lorentz-violating vector field background. The existence of stable BPS v´ortices implies in a null (kAF )0 component. The study shows that the influence of the Lorentz violation is clearly manifested when the vortex s winding number is greater than 1.
Esta dissertação apresenta o estudo de vórtices BPS num modelo obtido pela redução dimensional da eletrodinâmica de Maxwell-Carroll-Field-Jackiw-Higgs de (1+3)-dimensões para (1+2)-D. A densidade lagrangiana do modelo de Maxwell-Carroll-Field-Jackiw-Higgs é definido por L1+3 = −14 FμνFμν − 14 ϵμνκλ (kAF )μ AνFκλ + |Dμϕ|2 − V (|ϕ|), os dois primeiros termos constituem a eletrodin amica CPT- ímpar do modelo padrão estendido (SME). O termo ϵμνκλ (kAF )μ AνFκλ é o chamado termo de Carroll-Field-Jackiw. A redução dimensional deste modelo é dado pela seguinte densidade lagrangiana L1+2 = − 14 FμνFμν + s4 ϵμνκAμFνκ + 12 ∂μψ∂μψ −12 ϵμνκ (kAF )μ ψ∂νAκ − 12 ϵμκν (kAF)μ Aκ∂νψ + |Dμϕ|2 − e2ψ2 |ϕ|2 − V (|ϕ|2 , ψ), observamos que se (kAF)μ = 0 se obtém o modelo de Maxwell-Chern-Simons-Higgs (MCSH). Desse modo o modelo planar representa um modelo de MCSH modificado por uma interação entre o campo de gauge Aμ e o campo neutro ψ cuja constante de acoplamento é (kAF )μ, o campo de fundo vetorial portador dos efeitos da violação de Lorentz. Impondo que a componente (kAF)0 seja nula é possível estabelecer soluções estáveis tipo vórtices BPS. O estudo mostra que a influência da violação de Lorentz é manifesta claramente quando o winding number do vórtice é maior que 1.
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Andraud, Chantal. "Defauts d'empilement dans le materiau unidimensionnel cscdbr::(3) : etude spectroscopique." Paris 6, 1987. http://www.theses.fr/1987PA066140.
Повний текст джерелаАнотація:
L'etude des proprietes optiques de cscdbr::(3) a montre l'existence de centres br::(2)**(2-). L'excitation des echantillons par des rayonnements ionisants (rx, faisceau d'electrons) et des experiences d'absorption a deux photons ont permis d'associer les differentes bandes d'emission et d'absorption observees a des transitions appartenant a ces centres. L'existence de ces centres br::(2)**(2-) est attribuee a la presence de defauts d'empilement. L'effet d'une pression hydrostatique, le dopage par des ions pb**(2x) et le recuit des cristaux confirment l'hypothese
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Arrieta, Santiago Raul. "Papel do ecocardiograma transesofágico tridimensional na ótima seleção do dispositivo para o tratamento percutâneo da comunicação interatrial tipo ostium secundum." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/98/98131/tde-26042016-083838/.
Повний текст джерелаАнотація:
INTRODUCAO: A comunicação interatrial tipo \"ostium secundum\" é um defeito cardíaco congênito caracterizado pela deficiência parcial ou total da lâmina da fossa oval, também chamada de septo primo. Corresponde a 10 a 12% do total de cardiopatias congênitas, sendo a mais frequente na idade adulta. Atualmente a oclusão percutânea é o método terapêutico de escolha em defeitos com características anatômicas favoráveis para o implante de próteses na maioria dos grandes centros mundiais. A ecocardiografia transesofágica bidimensional com mapeamento de fluxo em cores é considerada a ferramenta padrão-ouro para a avaliação anatômica e monitoração durante do procedimento, sendo crucial para a ótima seleção do dispositivo. Neste sentido, um balão medidor é introduzido e insuflado através do defeito de forma a ocluí-lo temporariamente. A medida da cintura que se visualiza no balão (diâmetro estirado) é utilizada como referência para a escolha do tamanho da prótese. Recentemente a ecocardiografia tridimensional transesofágica em tempo real tem sido utilizada neste tipo de intervenção percutânea. Neste estudo avaliamos o papel da mesma na ótima seleção do dispositivo levando-se em consideração as dimensões e a geometria do defeito e a espessura das bordas do septo interatrial. METODO: Estudo observacional, prospectivo, não randomizado, de único braço, de uma coorte de 33 pacientes adultos portadores de comunicação interatrial submetidos a fechamento percutâneo utilizando dispositivo de nitinol autocentrável (Cera ®, Lifetech Scientific, Shenzhen, China). Foram analisadas as medidas do maior e menor diâmetro do defeito, sua área e as medidas do diâmetro estirado com balão medidor obtidas por meio das duas modalidades ecocardiográficas. Os defeitos foram considerados como elípticos ou circulares segundo a sua geometria; as bordas ao redor da comunicação foram consideradas espessas (>2 mm) ou finas. O dispositivo selecionado foi igual ou ate 2 mm maior que o diâmetro estirado na ecocardiografia transesofágica bidimensional (padrão-ouro). Na tentativa de identificar uma variável que pudesse substituir o diâmetro estirado do balão para a ótima escolha do dispositivo uma série de correlações lineares foram realizadas. RESULTADOS: A idade e peso médio foram de 42,1 ± 14,9 anos e 66,0 ± 9,4kg, respectivamente; sendo 22 de sexo feminino. Não houve diferenças estatísticas entre os diâmetros maior e menor ou no diâmetro estirado dos defeitos determinados por ambas as modalidades ecocardiográficas. A correlação entre as medidas obtidas com ambos os métodos foi ótima (r > 0,90). O maior diâmetro do defeito, obtido à ecoardiografia transesofágica tridimensional, foi a variável com melhor correlação com o tamanho do dispositivo selecionado no grupo como um todo (r= 0,89) e, especialmente, nos subgrupos com geometria elíptica (r= 0,96) e com bordas espessas ao redor do defeito (r= 0,96). CONCLUSÃO: Neste estudo em adultos com comunicações interatriais tipo ostium secundum submetidos à oclusão percutânea com a prótese Cera ®, a ótima seleção do dispositivo pôde ser realizada utilizando-se apenas a maior medida do defeito obtida na ecocardiografia transesofágica tridimensional em tempo real, especialmente nos pacientes com defeitos elípticos e com bordas espessas.INTRODUCTION: The ostium secundum atrial septal defect is a congenital heart disease characterized by partial or total deficiency of the fossa ovalis, also known as the septum primum. It corresponds to 10-12% of all congenital heart defects, being the most frequently found in adulthood. Currently, percutaneous closure is the therapeutic method of choice for defects with suitable anatomic features for device implantation in most centers in the world. Bi-dimensional transesophageal echocardiography with color flow mapping is considered the gold-standard tool for anatomic assessment and procedural monitoring, being crucial for optimal device selection. In this regard, a sizing balloon is introduced and inflated across the defect with temporary occlusion. The waist measurement seen on the balloon (stretched diameter) is used as a reference for selection of device size. Recently, real time three-dimensional transesophageal echocardiography has been utilized in this type of percutaneous intervention. In this study we assessed the role of this modality in optimal device selection taking into consideration the dimensions and the geometry of the defect and the thickness of the interatrial septum rims. METHODS: Observational, prospective, non-randomized, single-arm study of a cohort of 33 adults with atrial septal defects submitted to percutaneous closure using a self-centered nitinol device (Cera (TM), Lifetech Scientific, Shenzhen, China). The largest and the smallest diameter of the defect, its area and the measurements of the stretched diameter of the sizing balloon were assessed by both echocardiographic modalities. The defects were considered as elliptical or circular according to their geometry; the rims surrounding the defect were considered thick (> 2 mm) or thin. The selected device was equal to or 2 mm larger than the stretched diameter on bi-dimensional transesophageal echocardiography (gold-standard). In an attempt to identify a variable that could replace the stretched balloon diameter, a series of linear correlations were performed. RESULTS: The mean age and weight were 42.1 ± 14.9 years and 66.0 ± 9.4 kgs, respectively; being 22 of the female gender. There were no statistical differences between the largest and smallest diameters of the defects and the stretched diameters determined by both echocardiographic modalities. The correlation between the measurements obtained by both methods was excellent (r > 0.90). The largest defect diameter obtained by three-dimensional transesophageal echocardiography was the variable that showed the best correlation with the selected device size in the entire group (r= 0.89), especially in the subgroups with elliptical geometry (r= 0.96) and with thick rims surrounding the defect (r=0.96). CONCLUSIONS: In this study in adults with ostium secundum atrial septal defects submitted to percutaneous occlusion with the Cera (TM) device, optimal device selection could be performed using solely the largest diameter of the defect obtained by real time three-dimensional transesophageal echocardiography, especially in patients with elliptical defects and thick rims.
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Osman, Ahmad. "Automated evaluation of three dimensional ultrasonic datasets." Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00995119.
Повний текст джерелаАнотація:
Non-destructive testing has become necessary to ensure the quality of materials and components either in-service or at the production stage. This requires the use of a rapid, robust and reliable testing technique. As a main testing technique, the ultrasound technology has unique abilities to assess the discontinuity location, size and shape. Such information play a vital role in the acceptance criteria which are based on safety and quality requirements of manufactured components. Consequently, an extensive usage of the ultrasound technique is perceived especially in the inspection of large scale composites manufactured in the aerospace industry. Significant technical advances have contributed into optimizing the ultrasound acquisition techniques such as the sampling phased array technique. However, acquisition systems need to be complemented with an automated data analysis procedure to avoid the time consuming manual interpretation of all produced data. Such a complement would accelerate the inspection process and improve its reliability. The objective of this thesis is to propose an analysis chain dedicated to automatically process the 3D ultrasound volumes obtained using the sampling phased array technique. First, a detailed study of the speckle noise affecting the ultrasound data was conducted, as speckle reduces the quality of ultrasound data. Afterward, an analysis chain was developed, composed of a segmentation procedure followed by a classification procedure. The proposed segmentation methodology is adapted for ultrasound 3D data and has the objective to detect all potential defects inside the input volume. While the detection of defects is vital, one main difficulty is the high amount of false alarms which are detected by the segmentation procedure. The correct distinction of false alarms is necessary to reduce the rejection ratio of safe parts. This has to be done without risking missing true defects. Therefore, there is a need for a powerful classifier which can efficiently distinguish true defects from false alarms. This is achieved using a specific classification approach based on data fusion theory. The chain was tested on several ultrasound volumetric measures of Carbon Fiber Reinforced Polymers components. Experimental results of the chain revealed high accuracy, reliability in detecting, characterizing and classifying defects.
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Fong-Lin and 陳豐霖. "The Role of Real-Time Three-Dimensional Echocardiography in Congenital Septal Defects: Assessing and Guiding the Treatment Procedures for Atrial Septal Defect and Ventricular Septal Defect." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/42657016292355927292.
Повний текст джерелаАнотація:
博士中山醫學大學
醫學研究所
95
Background: Two-dimensional echocardiography (2DE) enhanced by combining with color Doppler technology has significant limitations in providing precise quantitative information, geometric assumptions to calculate chamber volume, mass, and ejection fraction. Reconstructed three-dimensional echocardiographic (3DE) systems (from multiple cross-sectional echocardiographic scans) are still cumbersome and time-consuming. Real-time 3DE (RT3DE) with shorter imaging time than with 3D reconstruction techniques can obtain qualitative and quantitative information on heart disorders. Our purpose was to estimate the patient of Atrial Septal Defect (ASD) and Ventricular Septal Defect (VSD). Transcatheter Amplatzer septal occluder (ASO) device closure of atrial septal defects (ASDs) has traditionally been guided by two-dimensional transesophageal echocardiography (2D-TEE) and intracardiac echocardiography (ICE) modalities. Real-time three-dimensional transthoracic echocardiography (RT3D-TTE) provides rotating images to define ASD and adjacent structures with potential as an alternative to 2D-TEE or ICE for guiding the device closure of ASD. There are two subjects of this study. The first subject was to assess the feasibility and effectiveness of RT3D-TTE in parasternal four-chamber views to guide ASO device closure of ASD. The second subject was to investigate the feasibility and potential value of RT3DE as a means of accurately and quantitatively estimating the size of VSD to correlate with the surgical findings. Materials and Methods: From February 2004 to August 2005, total 97 patients of septal defect were samples. Among in these patients, the 59 patients underwent transcatheter ASO device closure of ASD. The first 30 patients underwent 2D-TEE guidance under general anesthesia and the remaining 29 patients underwent RT3D-TTE guidance with local anesthesia. In addition, the 38 patients with VSD were examined with RT3DE. 3D image data-base was post-processed using TomTec echo 3D workstation. The results were compared with the results measured by 2 DE and surgical findings. Results: The first subject of atrial septal defect patients. All interventions were successfully completed without complications. The clinical characteristics and transcatheter closure variables of RT3D-TTE and 2D-TEE were compared. Echocardiographic visualization of ASD and ASO deployment was found to be adequate when using either methods. Catheterization laboratory time (39.1±5.4 vs 78.8±14.1 minutes, P < 0.001) and interventional procedure length (7.6±4.2 vs 15.3±2.9 minutes, P < 0.001) were shortened by using RT3D-TTE as compared with 2DE-TEE. There was no difference in the rate of closure following either method, assessed after a 6-month follow-up. The maximal diameter measured by RT3D-TTE and 2D-TEE was correlated well with a balloon stretched ASD size (y = 0.985x + 0.628, r = 0.924 vs y = 0.93x + 2.08, r = 0.885, respectively). The second subject of RT3DE produced novel views of VSD and improved quantification of the size of the defect. The sizes obtained from 3DE have equivalent correlation with surgical findings as diameter measured by 2-DE (r = 0.89 vs r = 0.90). Good agreement between blinded observers was achieved by little interobserver variability. Conclusion: RT3D-TTE may be a feasible, safe, and effective alternative to the standard practice of using 2D-TEE to guide ASO deployment. In addition, RT3DE offers intraoperative visualization of VSD to generate a “virtual sense of depth”without extending examining time. From an LV en face projection, the positions, sizes, and shapes of VSDs can be accurately determined to permit quantitative recording of VSD dynamics. It is a potentially valuable clinical tool to provide precise imaging for surgical and catheter-based closure of difficult perimembranous and singular or multiple muscular VSD.
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Kochhar, S. S. "Defence mechanisms and personality dimensions." Thesis, 1985. http://hdl.handle.net/2009/4298.
Повний текст джерела
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Wang, Z. H., and 王政輝. "PROPERTIES OF DEFECT MODES IN ONE-DIMENSIONAL PHOTONIC CRYSTALS." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/07299289598256272535.
Повний текст джерелаАнотація:
碩士國立臺灣師範大學
光電科技研究所
98
In this thesis, we have three topics. The first one is to study the defect modes in the asymmetric and symmetric multilayer narrowband transmission filters in the simple case of normal incidence. It is based on the wavelength-dependent transmittance calculated by making use of the transfer matrix method. In an asymmetric filter, there exists only one defect mode within the photonic band gap and its position can be changed when the design wavelength is varied. In a symmetric filter, it is found that there are two defect modes. Using Bloch wave approximation, these two defect modes respectively correspond to the symmetric and the asymmetric field solutions in the defect layer. The second part is to extend the first part to the oblique incidence for the same structures. The defect modes are investigated by the calculated wavelength-dependent transmittance for both TE and TM waves. The dependences of defect modes on the angle of incidence are illustrated. Additionally, the effect of defect thickness on the number of defect modes is also examined. The third part is to study the angle- and thickness-dependent photonic band structures in a one-dimensional superconducting photonic crystal. It is studied near and below the threshold frequency at which the superconducting material has a zero permittivity. The gap structure is analyzed as a function of the thicknesses of the two constituent superconducting and dielectric materials. In the angular dependence of the band structure, in TM-polarization, there exists a strongly localized superpolariton gap approximately the threshold frequency. This gap is shown to be enhanced as the angle increases.